Here, we report on the development of novel Zn-, Zn–Cr-, and Zn–Cu-containing catalysts using magnetic silica (Fe₃O₄–SiO₂) as the support. Transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) showed that the iron oxide nanoparticles are located in mesoporous silica pores and the magnetite (spinel) structure remains virtually unchanged despite the incorporation of Zn and Cr. According to XPS data, the Zn and Cr species are intermixed within the magnetite structure. In the case of the Zn–Cu-containing catalysts, a separate Cu₂O phase was also observed along with the spinel structure. The catalytic activity of these catalysts was tested in methanol synthesis from syngas (CO + H₂). The catalytic experiments showed an improved catalytic performance of Zn- and Zn–Cr-containing magnetic silicas compared to that of the ZnO–SiO₂ catalyst. The best catalytic activity was obtained for the Zn–Cr-containing magnetic catalyst prepared with 1 wt % Zn and Cr each. X-ray absorption spectroscopy demonstrated the presence of oxygen vacancies near Fe and Zn in Zn-containing, and even more in Zn–Cr-containing, magnetic silica (including oxygen vacancies near Cr ions), revealing a correlation between the catalytic properties and oxygen vacancies. The easy magnetic recovery, robust synthetic procedure, and high catalytic activity make these catalysts promising for practical applications.

中文翻译：

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金属离子分布和氧空位决定了甲醇合成中磁性可回收催化剂的活性

在这里，我们报告了使用磁性二氧化硅（Fe ₃ O ₄ -SiO ₂）为载体的新型Zn-，Zn-Cr-和Zn-Cu催化剂的开发。透射电子显微镜，粉末X射线衍射和X射线光电子能谱（XPS）表明，尽管掺入了Zn和Cr，但氧化铁纳米颗粒位于介孔二氧化硅孔中，磁铁矿（尖晶石）的结构实际上保持不变。根据XPS数据，Zn和Cr物种在磁铁矿结构内混合在一起。在含Zn-Cu的催化剂的情况下，还观察到一个单独的Cu ₂ O相以及尖晶石结构。在合成气（CO + H）合成甲醇中测试了这些催化剂的催化活性。₂）。催化实验表明，与ZnO-SiO ₂催化剂相比，含锌和含锌-铬的磁性二氧化硅的催化性能有所提高。对于分别使用1 wt％的Zn和Cr制备的含Zn-Cr的磁性催化剂，可以获得最佳的催化活性。X射线吸收光谱法表明，在含锌的Fe和Zn附近存在氧空位，在含Zn-Cr的磁性二氧化硅中存在更多的空位（包括Cr离子附近的氧空位），揭示了催化性能与氧之间的相关性空缺。易于磁回收，稳健的合成程序和高催化活性，使这些催化剂在实际应用中大有希望。